JPH0375767A - Developing device for electrophotographic device - Google Patents

Abstract

PURPOSE:To eliminate unequal development and to prevent the degradation in recording quality by pressing a developing roller to a photosensitive body to deform the roller and pressing space rollers at both ends thereto to maintain the specified distance between the centers of the photosensitive body and the developing roller. CONSTITUTION:The developing roller 33 is constituted of the rubber roller 40 and the space rollers 41. The roller 40 is made of conductive rubber and is constituted to impress a bias voltage between the same and the photosensitive body 15. The rollers 41 are made of a material which does not cause elastic deformation. These rollers are formed to the diameter smaller than the diameter of the roller 40. The roller 40 is energized by a compressing spring 38 and is pressed to the photosensitive body 15 at this time, by which the roller 40 is deformed and the roller width is generated. The rollers 41 are pressed to this roller to maintain the specified distance between the centers of the photosensitive body 15 and the roller 33. The rollers 40, 41 are provided coaxially at both ends and do not cooperate with each other. The one-component magnetic toner 32 sticking to the roller 40 can be transferred to the photosensitive body 15 when the roller 40 is rotated at the speed higher than the speed of the photosensitive body 15 and the rollers 41 are brought into contact with the photosensitive body 15 and are rotated at the same speed. The electrostatic latent images of the photosensitive body 15 are developed to visible images in this way. The unequal development is thereby eliminated and the degradation in the recording quality is prevented.

Description

[Detailed Description of the Invention] This invention is a printer, facsimile, and printer using a laser.
The present invention can be applied to electrophotographic devices such as copying machines and printing machines that perform recording on a recording medium such as paper using an electrophotographic process. More specifically, the present invention relates to a developing device in such an electrophotographic apparatus that attaches one-component nonmagnetic toner to a photoreceptor and visualizes an electrostatic latent image formed on the surface of the photoreceptor.

Traditionally, in this type of developing device, a spring bias is applied, for example, the seventh
As shown in the figure, a rubber developing roller 2 is pressed against a drum-shaped photoreceptor 1 that does not have elasticity, and both are rotated in the direction of the arrow in the figure to uniformly adhere to the surface of the developing roller 2. The component non-magnetic toner was transferred to the photoreceptor 1, and the electrostatic latent image on the surface of the photoreceptor 1 was visualized.

In this type of conventional developing device, the amount of deformation of the developing roller 2 varies depending on the rubber hardness of the developing roller 2 and the spring biasing force biased toward the photoreceptor 1. When the amount of deformation of the developing roller 2 changes, there is a problem in that uneven development such as self-dropping and shading occurs, resulting in a decrease in recording quality.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve such conventional problems in a developing unit of an electrophotographic apparatus, to prevent uneven development by keeping the amount of deformation of the developing roller at a constant value, and to prevent deterioration in recording quality. It's about doing.

Means for Solving the Problems Therefore, in the present invention, for example, as shown in the illustrated embodiment below, the developing roller 33 is biased by a compression spring 38.
is pressed against a drum-shaped photoreceptor 15 that does not have elasticity,
The one-component non-magnetic toner 32 is uniformly adhered to the surface of the developing roller 33 by rotating them together, and the one-component non-magnetic toner 32 is applied to the photoreceptor 15.
In the developing device 18 of an electrophotographic apparatus that transfers the electrostatic latent image to the surface of the photoreceptor 15 and visualizes it, the developing roller 33 is composed of a rubber roller 40 and a space roller 41, and the rubber roller 40 is composed of a rubber roller 40 and a space roller 41. , is made of conductive rubber, and a bias voltage is applied between it and the photoreceptor 15-, and the one-component non-magnetic toner 32 is uniformly adhered thereto; the space roller 41 is made of a material that does not cause elastic deformation; It is characterized in that it is made to have a smaller diameter than the rubber roller 40, and is not interlocked with the rubber roller 40, but is provided at both ends on the same axis.

Then, the rubber roller 40 of the developing roller 33 is pressed against the drum-shaped photoreceptor 15 with a spring bias.
0 is deformed and the space rollers 41 at both ends are pressed against each other to keep the distance between the centers of the photoreceptor 15 and the developing roller 33 constant. Then, the photoreceptor 15 and the developing roller 33 are rotated together, and the one-component non-magnetic toner 32 that is uniformly adhered to the rubber roller 40 is transferred to the photoreceptor 15 to make the electrostatic latent image on the photoreceptor 15 visible. Visualize.

Husband - hair salon Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 6 is a laser printer shown as an example of an electrophotographic device, and the reference numeral 1 in FIG.
0 is the main body of the device. On the right side of the device main body 10 in the figure,
A paper feed cassette 11 is detachably attached. Then, the paper 12 stored in the paper feed cassette 11 is transferred to the paper feed roller 1.
3, feed the register roller pair 14 in the direction of the arrow in the figure.
Hit it and stop it. On the other hand, in the main body 10 of the apparatus, a drum-shaped photoreceptor 15 having no elasticity is housed in the center. As it rotates clockwise in the figure, it is first charged with a charger 16 to uniformly charge its surface, and then exposed with a writer 17 to form an electrostatic latent image on its surface. Thereafter, the electrostatic latent image is developed into a visible image using the developing device 18 according to the present invention. Thereafter, the pair of registration rollers 14 described above are rotated in accordance with the rotation of the photoreceptor 15.
The above-mentioned paper 12 that had been abutted against it is guided between the photoreceptor 15 and the transfer device 19. Then, the image on the photoreceptor 15 is transferred to the paper 12 by the transfer device 19, and the image is sent to the fixing device 20 where it is fixed. Thereafter, the paper is sent out in the direction of arrow B in the figure through the paper discharge path 21 and stacked on the paper discharge receiver 22. On the other hand, the cleaning blade 24 of the cleaning device 23 scrapes off the residual toner on the surface of the photoreceptor 15 after the transfer, and the static eliminator 25 removes the static electricity. Then, it is charged again by the charger 16.

Incidentally, as shown in FIG. 5, the developing device 18 according to the present invention has a toner cartridge 31 replaceably attached to a developing case 3o, and a one-component non-magnetic toner 32& stored in the developing case 30.

Inside the developing case 30, a developing roller 33. a toner replenishment roller 34 that replenishes the developing roller 33 and adheres the toner 32 to its surface; an agitator 35 that agitates the toner 32 and sends it to the toner replenishment roller 34; Developing roller 33
A blade 36 that equalizes the thickness of the toner 32 that adheres to the
Equipped with etc.

The developing roller 33 is pressed against the photoreceptor 15 by a compression spring 38 which is mounted on the case 37 and biases the case 37. As a result, both the photoreceptor 15 and the developing roller 33 rotate, and the one-component non-magnetic toner 32 uniformly adhered to the surface of the developing roller 33 is transferred to the photoreceptor 15, and the electrostatic potential on the surface of the photoreceptor 15 is transferred to the photoreceptor 15. Visualize the image. Photoreceptor 1
5. The developing roller 33, the toner supply roller 34, and the agitator 35 each rotate in the direction of the arrow in the figure.

Now, in the developing device 18 according to the present invention, the developing roller 33
is composed of a rubber roller 40 and a space roller 41, as shown in FIG. The rubber roller 40 is made of conductive rubber, and a bias voltage is applied between it and the photoreceptor 5 as shown in FIG. On the other hand, the space roller 41 is made of a material that does not undergo elastic deformation and has a smaller diameter than the rubber roller 40. As can be seen from FIG. 1, the rollers are provided at both ends of the rubber roller 40 coaxially so that they rotate without interlocking with the rubber roller 40.

The developing device 18 according to the present invention is constructed as described above.

Therefore, the rubber roller 40 of the developing roller 33 is pressed against the drum-shaped photoreceptor 15 by the compression spring 38, and the rubber roller 40 is deformed to create a developing width Q as shown in FIG. The distance between the centers of the photoreceptor 15 and the developing roller 33 is kept constant by pressing the space roller 41 against it.

Then, as shown in FIG. 1, the photoreceptor 15 is rotated at v8, the rubber roller 40 is rotated at a faster speed of v2,
When the space roller 41 is in contact with the photoreceptor 15, the same V is applied.
It rotates in the process. As a result, the one-component non-magnetic toner 32 that adheres uniformly to the rubber roller 40 is transferred to the photoreceptor 15,
The electrostatic latent image on the photoreceptor 15 can be visualized.

As shown in the third @, the diameter of the photoreceptor 15 is A.

The diameter of the rubber roller 40 of the developing roller 33 is defined as d, and the diameter of the space roller 41 of the developing roller 33 is defined as d.

The development width is assumed to be R as described above. Further, as shown in FIG. 4, the center of the photoreceptor 15 is set to O8, the center of the developing roller 33 is set to 0□, and the point where the photoreceptor 15 and the rubber roller 40 begin to contact is m, and then the center is set to O□. 0□
Draw a perpendicular line to the line connecting and let the intersection with that line be n, the distance between the center 0□ and the intersection n be a, and the distance between the contact point of the photoreceptor 15 and the space roller 41 and the intersection n be b. . Then, the distance between point m and intersection n becomes g/2. Therefore.

Three first-order equations are established from the Pythagorean theorem.

a + b = A/2 a”+ (Q/2) ”= (A/2) ”(b + d
/2) 2+ (fi/2) ”= (D/2) ”From these three formulas, the development width ratio is calculated.

Party = 2f1πP: (((A/2+d/2) '+ (A/2) ”-■/
2) ”) / (2(A/2+d/2) ) ) ”
Therefore, when the diameter A of the photoreceptor 5 is determined, the development width α is determined by the diameter of the rubber roller 40 and the space roller 4.
It can be freely determined by appropriately selecting the diameter d of 1. In other words, the development width overflow can be determined without being influenced by the biasing force of the compression spring 38 or the rubber hardness of the rubber roller 40.

Therefore, according to the present invention, it is not affected by the spring urging force that presses the developing roller against the photoreceptor or the rubber hardness of the rubber roller of the developing roller.

Since the development width is set to a constant value, it is possible to prevent development unevenness due to these variations and prevent deterioration in recording quality.

[Brief explanation of drawings]

1 to 6 show a developing device which is an embodiment of the present invention, FIG. 1 is a perspective view of a developing roller of the developing device and a photoreceptor against which it is pressed, and FIG. 2 is a perspective view of the photoreceptor. 3 and 4 are dimensional symbol diagrams of each part of FIG. 1, respectively, and FIG. 5 is an illustration of applying a bias voltage between the rubber roller of the developing device and energizing explanatory diagram,
FIG. 6 is an overall schematic diagram of the internal mechanism of a laser printer equipped with the developing device. FIG. 7 is a perspective view of a developing roller of a conventional developing device and a photoreceptor against which it is pressed. 15......Photoreceptor, 32......
・One-component non-magnetic toner, 33...Developing roller, 38...Compression spring, 40...
...Rubber roller, 41... Space roller.

Claims (1)

[Claims] A developing roller is biased by a spring and pressed against a drum-shaped photoreceptor that does not have elasticity, and they are rotated together to produce monocomponent non-magnetic toner that is uniformly adhered to the surface of the developing roller. In a developing device of an electrophotographic device that transfers to the photoreceptor and visualizes an electrostatic latent image on the surface of the photoreceptor, the developing roller includes a rubber roller and a space roller, and the rubber roller is made of conductive rubber. The space roller is made of a material that does not undergo elastic deformation and has a smaller diameter than the rubber roller, and a bias voltage is applied between the space roller and the photoreceptor to uniformly adhere the one-component non-magnetic toner. A developing device for an electrophotographic device is not linked to the rubber roller, but is installed on both ends of the same axis.